Benchmarking the Geomagnetically Induced Currents Related Harmonics Analysis Tool (GICharm) Against Time-Domain Simulation

The analysis of Geomagnetically Induced Current (GIC) flows at a system scale is a relatively mature feature of bulk power system planning tools. The study of GIC-related harmonics mitigation strategies at the system scale is still a gap in the industry. EPRI developed the publicly available GIC-related harmonic analysis tool (GICharm) with the objective of addressing this gap. As a continuation of the efforts to increase industry confidence in GICharm, this paper compares its accuracy against time domain simulations using the commercial software tool EMTP. The paper utilizes the well-known Western System Coordinating Council (WSCC) 9-bus system under a Geomagnetic Disturbance (GMD) scenario. Frequency scans, voltage and current waveforms, and Voltage Total Harmonic Distortion (VTHD) are obtained from both tools and compared to provide a high level of detail. A brief computational-time comparison discussion is also included. The paper also discusses all the necessary modeling details for each component in the test system, starting from publicly available positive-sequence information. It also describes the assumptions made to define a multi phase model from the positive-sequence information, as well as the steps taken to create both GICharm and EMTP models.